When customising a WA site I find the best tool is the "inspect element" feature in Firefox and Chrome (in the menu when you right click). The WA website structure has so many layers of DIV's it is often hard to work out which one is effecting your layout. With the inspect element tool you can select the object you want to customise, see what CSS is controlling it and even experiment with changing the code and see how the browser will display it without making any actual changes to you site.

As for the members name when logged in, I think the following will probably do the job: